Möbius String Robot Goes Round And Round

While it doesn’t look like a traditional robot, the hydrogel robot from [Zi Liang Wu] forms a möbius strip and can be activated by light. They also experimented with shaping the hydrogels as a Seifert ribbon.

The key is that the hydrogels contain gold nanoparticles. Light heats the gold particles and this causes the hydrogels to move. The connections between the strips of hydrogels causes them to move in predictable ways. You can see a video about the experiments below.

These robots aren’t going to be for warehouse or factory work. But they can do tasks like collecting plastic beads, something difficult for conventional robots to do. They also hope to demonstrate that these soft robots could work in the body for taking samples or delivering a drug, although it isn’t apparent how light would get to them inside your body.

The dark side of the material tends to turn towards the light. The continuous loop structure means it never runs to the end of its travel. Watching it move on a string is pretty impressive.

Crawling and slithering robots may be the answer for certain specialized applications. After all, it works well in nature.

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Using Electroadhesion To Reversibly Adhere Metals And Graphite To Hydrogels And Tissues

The usual way to get biological tissues and materials like gels and metals to stick together is using sutures, adhesives or both. Although this generally works, it’s far from ideal, with adhesives forming a barrier layer between tissues and the hard or impossible to undo nature of these methods. A viable alternative might be electroadhesion using cation and anion pairs, which uses low-voltage DC to firmly attach the two sides, with polarity reversal loosening the connection with no permanent effects. This is what a group of researchers have been investigating for a few years now, with the most recent paper on the topic called Reversibly Sticking Metals and Graphite to Hydrogels and Tissues by [Wenhao Xu] and colleagues published this year in ACS Central Science.

This follows on the 2021 study published in Nature Communications by [Leah K. Borden] and colleagues titled Reversible electroadhesion of hydrogels to animal tissues for suture-less repair of cuts or tears. In this study a cationic hydrogel (quaternized dimethyl aminoethyl methacrylate, QDM) was reversibly bonded to bovine aorta and other tissues, with said tissues functioning as the anionic element. Despite demonstrated functionality, the exact mechanism which made the application of 3-10 VDC (80 – 125 mA) for under a minute (10+ seconds) cause both sides to bond so tightly, and reversibly, is still unknown. This is where the recent study provides a mechanism and expands the applications.

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Printed Brain Implants Give New Meaning To Neuroplasticity

3D printing has opened up a world of possibilities in plastic, food, concrete, and other materials. Now, MIT engineers have found a way to add brain implants to the list. This technology has the potential to replace electrodes used for monitoring and implants that stimulate brain tissue in order to ease the effects of epilepsy, Parkinson’s disease, and severe depression.

Existing brain implants are rigid and abrade the grey matter, which creates scar tissue over time. This new material is soft and flexible, so it hugs the wrinkles and curves. It’s a conductive polymer that’s been thickened into a viscous, printable paste.

The team took a conductive liquid polymer (water plus nanofibers of a polystyrene sulfonate) and combined it with a solvent they made for a previous project to form a conductive, printable hydrogel.

In addition to printing out a sheet of micro blinky circuits, they tested out the material by printing a flexible electrode, which they implanted into a mouse. Amazingly, the electrode was able to detect the signal coming from a single neuron. They also printed arrays of electrodes topped with little wells for holding neurons so they can study the neurons’ signals using the electrode net underneath.

This particular medical printing hack is pretty far out of reach for most of us, but not all of them are. Fire up that printer and check out this NIH-approved face shield design.

Syringe Pump Turns CNC Machine Into A Frosting Bot

“Amazing how with only the power of 3D-printing, two different computers, hundreds of dollars in CNC machinery, a lathe, and modern microcontroller magic, I can almost decorate a cupcake as well as a hyperactive ten-year-old.”  We can think of no better way to sum up [Justin]’s experiment in CNC frosting application, which turns out to only be a gateway to more interesting use cases down the road.

Granted, it didn’t have to be this hard. [Justin] freely admits that he took the hard road and made parts where off-the-shelf components would have been fine. The design for the syringe pump was downloaded from Thingiverse and does just about what you’d expect – it uses a stepper motor to press down on the plunger of a 20-ml syringe full of frosting. Temporarily attached in place of the spindle on a CNC router, the pump dispenses onto the baked goods of your choice, although with an irregular surface like a muffin top the results are a bit rough. The extruded frosting tends to tear off and drop to the surface of the cake, distorting the design. We’d suggest mapping the Z-height of the cupcake first so the frosting can dispense from a consistent height.

Quality of the results is not really the point, though. As [Justin] teases, this hardware is in support of bioprinting of hydrogels, along with making synthetic opals. We’re looking forward to those projects, but in the meantime, maybe we can all just enjoy a spider silk beer with [Justin].

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Genetically Engineered Muscle Cells Power Tiny Bio-Robots

One of the essential problems of bio-robotics is actuators. The rotors, bearings, and electrical elements of the stepper motors and other electromechanical drives we generally turn to for robotics projects are not really happy in living systems. But building actuators the way nature does it — from muscle tissue — opens up a host of applications. That’s where this complete how-to guide on building and controlling muscle-powered machines comes in.

Coming out of the [Rashid Bashir] lab at the University of Illinois at Urbana-Campaign, the underlying principles are simple, which of course is the key to their power. The technique involves growing rings of muscle tissue in culture using 3D-printed hydrogel as forms. The grown muscle rings are fitted on another 3D-printed structure, this one a skeleton with stiff legs on a flexible backbone. Stretched over the legs like rubber bands, the muscle rings can be made to contract and move the little bots around.

Previous incarnations of this technique relied on cultured rat heart muscle cells, which contract rhythmically of their own accord. That yielded motion but lacked control, so for this go-around, [Bashir] et al used skeletal muscle cells genetically engineered to contract when exposed to light. Illuminating different parts of the muscle ring lets the researchers move the bio-bots anywhere they want. They can also use electric stimulation to control the bio-bots.

The method isn’t quite at the point where home lab biohackers will start churning out armies of bio-bots. But the paper is remarkably detailed in methods and materials, from the CAD files for 3D-printing the forms and bio-bot skeletons to a complete troubleshooting guide. It’s all there, and it could be a game changer for developing the robotic surgeons of the future.

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